The manufacture of composite plastic assemblies such as instrument panels, vehicle interior parts and the like as well as other assemblies having a plastic foam layer is accomplished by use of mold apparatus in which foam precursors are poured through an opening in one of the component parts of the mold apparatus. One problem is to provide a seal at the opening to prevent the escape of the foam from the mold during the foaming process.
Another problem arises in such manufacture when it is necessary to precisely locate an insert component in a mold cavity so that the foam material will be formed with respect to the insert to form a replicate of a design configuration in which the insert is at an exact dimensional relationship with respect to the foamed portions of the finished product.